Aerosol consortium
Names and contact details for chairs:
Matthias Bigler (Bern, +41 (0)316318673, bigler@climate.unibe.ch)
Anders Svensson (Copenhagen, +45 35320616, as@nbi.ku.dk)
Margareta Hansson (Stockholm, +46 (0)86747865, margareta.hansson@natgeo.su.se)
Point of contact and procedure for joining the consortium mailing list
Please go to https://mailman.nbi.ku.dk/listinfo to sign up for the NEEM-aerosols mailing list. The list is managed by the consortium chairs.
A brief description of the work of the consortium
Apart from frozen water and enclosed air bubbles, ice cores contain a wide range of impurities which were deposited onto the ice sheet during past times. Impurity sources are manifold and comprise e.g. arid regions (mineral dust aerosol), oceans (sea salt aerosol), the terrestrial biosphere, volcanic eruptions, atmospheric processes, extraterrestrial origin and anthropogenic emissions. In addition to the strengths of these sources, also the atmospheric transport conditions to the ice sheets are decisive, regarding the amount of impurities found in the ice.
Some of the impurities are irreversibly deposited and reflect past atmospheric concentrations at the deposition site, considering the manner of deposition (wet or dry deposition). Hence, they can be used to reconstruct past source strengths and/or atmospheric transport conditions. Another important issue is to specify the provenances of specific impurities in case of different possible sources, e.g. for mineral dust. Furthermore, cosmogenic nuclides reveal information on past geomagnetic events and enable the reconstruction of the past solar activity.
As most of the aerosol species show distinct seasonal variation, either due to seasonal changes in the source or the transport properties, they can be used to date the ice core by annual layer counting, provided that seasonal layers are preserved and resolvable by the applied measuring technique. Furthermore, prominent layers, originating e.g. from large volcanic eruptions, can be used to synchronize ice cores and other marine or terrestrial archives. If even the dates of such layers are known, it is possible to pin down the annual layer counting to this reference horizons.
Other species are volatile or reactive and show concentration changes dependent on e.g. temperature, accumulation rate or sunshine duration. They are used to examine glacio-chemical processes related to aerosol deposition and preservation in the ice and can reveal information concerning the parameters mentioned above.
The NEEM Aerosol Consortium coordinates measurements and interpretations of impurity records gained from the NEEM ice core. Different labs from different countries are involved, applying different measuring techniques, such as continuous flow analysis, ion chromatography, mass spectrometry, particle counting and many more. All have to deal with the usually very low concentrations of impurities in polar ice cores and the only limited amount of sample available.